Installation for the evacuation of rocks from a working to a continuous transporter

ABSTRACT

The invention relates to the removal of rocks or stones from workings, for example a quarry or an open-cast mine. It concerns more particularly an installation for the evacuation of rocks or stones from a workings to a continuous transporter or conveyor. This installation comprises a chassis movable over the ground of the workings, a carriage movable on a rolling path along the continuous transporter or conveyor, a jib connecting the chassis to the carriage and consisting of a first arm carrying a continuous conveyor and a second arm carrying another continuous conveyor, both arms being articulated to one another on a substantially vertical pivot suspended from a structure which is supported by the chassis or by the carriage. The first arm of the jib is articulated to the chassis on a substantially vertical pivot, and the second arm is articulated to the carriage round another vertical pivot which comprises a trunnion rotatably mounted in a bearing round a substantially vertical axis, the trunnion being articulated to the end of the second arm round an axis which is substantially horizontal and substantially transverse to the conveyor of the second arm, and the bearing being articulated to the carriage round an axis which is substantially horizontal and substantially transverse to the continuous transporter or conveyor, said horizontal axes being situated substantially in the same plane.

United States Patent [1 1 Plaquet et INSTALLATION FOR THE EVACUATION OF ROCKS FROM. A WORKING TO A CONTINUOUS TRANSPORTER [76] Inventors: JacquesJules Plaquet, Chateau de Vaulx, 7520 Vaulx; Raymond Gerard Van Swieten, Dreve du Prince, 7504 Rumillies, both of Belgium 22 Filed: Sept.22, 1971 21 Appl. No.: 182,644

[30] Foreign Application Priority Data Sept. 25, 1970 Belgium 94,358/70 52 [1.8. (:1. 198/36 [51 1111.01. ..B65g 65/28 [58] Field of Search 198/92, 36, 220, 5 198/88 [56] References Cited UNITED STATES PATENTS 3,358,809 12/1967 Sukurs et'aL. 198/36 3,314,525 4/1967 Krause et al. 198/36 3,653,486 14 1972 McLean an... 198/36 3,598,224 2/1971 Oury 198/36 3,151,732 10 1961 0uryetal..;.1 198/92 3,583,553 6/197 -Spurlin et al. 198/220 Primary Examiner-Edward A; Sroka Att0mey-lrvin S. Thompson et al.

1 1' July 10,1973

57 ABSTRACT The invention relates to the removal of rocks or stones from workings, for example a quarry or an open-cast mine. It concerns more particularly an installation for the evacuation of rocks or stones from a workings to a continuous transporter or conveyor. This installation comprises a chassis movable over the-ground of the workings, a carriage movable on a rolling path along the continuous transporter or conveyor, a jib connecting the chassis to the carriage and consisting of a first arm carrying a continuous conveyor and a second arm carryinganother continuous conveyor, both arms being articulated to one another on a substantially vertical pivot suspended from a structure which is supported by the chassis or by the carriage. The first arm of the jib is articulated to the chassis on a substantially vertical pivot, and the second arm is articulated to the carriage round another vertical pivot which comprises a trunnion rotatably mounted in a bearing round a substantially vertical axis, the trunnion being articulated to the end'of the second arm round an axis which is substantially horizontal and substantially transverse to the conveyor of the second arm, and the bearing being articulated to the carriage round an axis which is substantially horizontal and substantially transverse to the con- .tinuous transporter or conveyor, said horizontal, axes being situated substantially in the same plane.

7 Claims, 16 Drawing Figures PAIENIEL-JUL 1 0 @915 SEE? 010! 15 PAIENIH] JUL 1 0 I973 SIEI 020$ 15 PATENTEB JUL 1 01915 SNEH IBM 15 Pmmeuw 3.744.615

sum UBBF 15 PATENIEU JUL 1 mm saw user 15 PATENIEU 117N975 3,744,615

saw 110$ 15 PATENTEUJUUOISH 3.744515 SHEEI 130$ 15 INSTALLATION FOR THE EVACUATION OF ROCKS FROM A WORKING TO A CONTINUOUS TRANSPORTER DESCRIPTION OF THE INVENTION The invention relates to the removal of rocks or stones from workings, for example a quarry or an opencast mine. It concerns for example the removal of barren rocks or minerals covering a deposit and taking them to a treatment unit situated away from the deposit.

The transfer or rocks from an exploitation zone of workings to a treatment unit is usually effected by lorries or by means of other automotive vehicles. A disadvantage of this type of transport lies in the fact that it is essentially discontinuous. It necessitates moreover considerable investment in material and a substantial number of personnel, not only for driving these vehicles but also fortheir maintenance. This method of transport has the additional disadvantage of the difficulty in negotiating hilly ground and it involves the necessity of laying out tracks for carrying these vehicles. In particular, in the case of deep workings in a quarry or open-cast mine, it is necessary to provide terraced access roads between the workings and the utilisation zone, in this instance a treatment unit.

is known that to effect a rapid and simple removal of rocks from workings, it is advantageous touse continuous conveyors, for example conveyor belts. These continuousconveyors are in fact of simple and automatic operation and only require a limited-number of personnel. They enable rapid conveyance of rocks over limited distance, in view of the fact that the length of overhang is limited by considerations of rigidity of the structure and balancing of the installation. The greatervment of the chassis'over the floor of the workings,

. which is particularly difficult and. necessitates compelong distances, for example up to a treatment unit situated away from the workings- The arrangement of continuous conveyors of this type necessitates an expensive substructure and suitable preparation of the ground, so that it is of prime im portance to establish'them away from an exploitable deposit, or failing this, in a zoneof the deposit where exploitation is only foreseen in the distant future.

To transfer of'extracted rocks from the zone of exploitation of the deposit to the continuous conveyor requires therefore an intermediate handling means.

It is known for this purpose to make use ofan installation which moves over the floor of the workings in the immediate vicinity of the exploitation zone and comprising a chassiswhich can move over the floor of the workings, a jibfixed to the chassis and extending over the continuous conveyor, a conveying device on' the jib and a means for, feeding the conveying device with rocks. The conveying device provided'on the jib can be for example a continuous conveyor of the belt type or pallet type. The means for feedingthe conveying device with rocks'to be removed can be a hopper, fed by an excavator shovel or other extraction device. The chassis is generally mounted on caterpillars in order to facilitate its movement over the floor of the workings and so that it can follow therefore the working face If necessary it could be mounted on series of tyred wheels.

\Vithan installation of this type it is sufficient to suitably guide the jib in order that its end is situated above the continuous conveyor: thus the rocks removed by the conveying device provided on the jib are pouredby gravity on to this continuous conveyor.

Thisknown installation hasunfortunately, the disad' vantage of only permitting the removal of rock over a tent personnel.

According to the invention there is provided an installation for the evacuation of rocks or stones from a workings to a continuous transporter or conveyor, comprising a chassis movable over the ground of the workings, a carriage movable on a rolling path along the continuous transporter or-conveyor, a jib connecting the chassis to the carriage and consisting of a first arm and a second arm articulated to one anotheron a substantially vertical pivot, the first arm being articulatedto the chassis on a substantially vertical pivot and the second arm being articulated to the carriageround another substantially vertical pivot, the first arm carrying a first continuous conveyor which discharges onto a second continuous conveyor carried bythe second arm of the jib, the second conveyor discharging onto the continuous transporteror conveyor, in which the common articulation pivot of the two arms of the jib is suspended from a structurewhich is supported by the chassisor by the carriage and in which the pivot of; articulation of the second arm on the carriage comprises a trunnion rotatably mounted in a bearing round a substantially vertical axis, the trunnion or the bearing being articulated to the end of the second arm round an axis which is substantially horizontal and'substantially transverse to the conveyor of the second arm, and the bearing of the trunnion being articulated to the carriage round an axis which is substantially horizontal and substantially transverse to the continuous transporter or conveyor,said horizontal axes being situated substantially in the same plane. 5 a

In the installation according to the invention the jib, constituted by two successive articulated arms, rests at one end on the chassis which can move'over the floor of theworkings and at the other end onthe carriage arranged in the vicinity of, the continuous conveyor. There is thus eliminated the overhang of the jib so that the latter can be very long without. prejudicing the equilibrium of the installationnor its stability,

Furthermore, in view of the fact that the jib is formed by two arms articulated to one another'and also to the chassis and to the carriage and that. the latter is fixed to a roller track along the continuous conveyor, it will be understood that during the movement of the chassis over the floor of the workings, the end of the jib is constantly maintained above the continuous conveyor. During the movement of the chassis over the floor of the working and/or during the movement of the carriage along its roller track, the two arms of the jib behave in the manner of the two arms of a pair of drawing compasses, so that the chassis can easily approach the continuous conveyor or on the contrary move away therefrom up to a distance equal,at maximum, to the complete spreading of the two arms of the jib this dischassis.

tance can be very large for the reasons explained previously.

In order to prevent the carriage from leaving the roller track under the action of a transverse force following complete spreading of the arm of the jib, it can be advantageous to provide on the two arms a warning device indicating to the operator when the angle between the two arms is near to 180.

In a special form of embodiment of the installation in accordance with the invention, the articulation pivot common to the two arms of the jib comprises a trunnion mounted rotationally in a bearing about a substantially vertical axis; this trunnion is articulated at the end of one of the arms about a substantially horizontal axis substantially transverse to the conveying device of the arm, and thebearing is articulated at the end of the other arm about a substantially horizontal axis substantially transverse to the conveying device of the other arm, the two horizontal axes being situated substantially in the same plane.

As a variant the articulation pivot of the first arm on the chassis can comprise a trunnion mounted rotationally in a bearing about a substantially vertical axis, the bearing being mounted on a frame which can swivel on the chassis and the trunnion being fixed to a support ar ticulated at the end of the first arm about a substantially horizontal axis substantially transverse to the conveying device of the arm. The respective positions of the trunnion and of the bearing can be reversed.

This variant of the installation according to the invention is specially adapted to the case of uneven workings. In fact it makes it possible to maintain in horizontal position the transverse axes of the respective conveying devices of the two arms of the jib, whatever the inclination of the ground over which the chassis moves. For this purpose it is sufficient to swivel the frame appropriately at any time on the chassis so as to keep constantaly vertical the axis of rotation of the articulation pivot of the first arm on the chassis. In order to facilitate the appropriate swivelling of the frame on the chassis, advantageously there can be provided an automatic stabilising device connecting the frame to the In view of the great length which the jib might have, this form of embodiment of the installation according to the invention can easily be used in the case of a deep quarry or mine in which the difference in levels between the continuous conveyor and zone of exploitation is considerable.

In the machine according to the invention,it can be advantageous to provide a device making it possible to lock the horizontal axis of rotation of the pivot on the carriage, when the latter is stopped, so as to fix the axis of rotation of the pivot vertically and to thus prevent twisting of the jib, for example through oscillation of the latter under the action of a side wind.

With a view to increasing the possibilities of the in- ,stallation according to the invention, it can comprise in a modified form of embodiment, a second jib connecting the chassis or the carriage to a vehicle movable over the ground of the workings, the second jib comprising a first arm which is articulated to the chassis or to the carriage on a substantially vertical pivot and a second arm which is articulated to the vehicle on a substantially vertical pivot, the two arms being further articulated to one another on a substantially vertical common pivot which is suspended from a structure supported by the vehicle or the chassis or carriage, the two arms of the second jib respectively carrying two continuous conveyors which discharge from one to the other and connect the vehicle to the chassis or to the carriage.

In this modified form of embodiment of the installation according to the invention, the vehicle can be made in a similar manner to the chassis. It can for example be mounted on caterpillars or on tyres; according to the type of ground over which it is intended to manoeuvre.

The utilisation of a second jib makes it possible to considerably increase the reach of the installation according to the invention between the zone of extraction and the continuous conveyor, when the second jib'connects the vehicle to the chassis.

In the case in which the second jib connects the vehicle to the carriage, the installation according to the invention makes it possible to feed the continuous conveyor starting from two separate extraction zones of the workings, and consequently to increase considerably the rate of flow of extracted and removed rocks.

In this modified form of embodiment of the installation according to the invention, the connection of the second jib to the vehicle and, if necessary, to the chassis can be effected in a similar manner to the connection of the first jib to the chassis.

When the second jib joins the vehicle to the carriage of the installation, its articulation pivot to this carriage can advantageously be similar to the articulation pivot, in accordance with the invention, of the first jib on the carriage.

It can likewise be advantageous if the articulation pivot common to the two arms of the second jib comprises in accordance with the invention, a trunnion rotatably mounted in a bearing round a substantially vertical axis, the trunnion being articulated to the end of one of the arms, round an axis which is substantially horizontal and substantially transverse to the conveyor of the arm and the bearing being articulated to the end of the other arm, round an axis which is substantially horizontal and substantially transverse to the conveyor of the other arm, the two horizontal axes being situated substantially in the same plane.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which FIGS. la and lb show in elevation a first form of embodiment of the installation according to the invention, in which the two arms of the jib are arranged in alignment with one another, the two Figures joining with one another at the line A-A,

FIG. 2,

FIG. 5 is, on a larger scale, an outline view of the installation represented in FIGS. 1 and 2, viewed in the direction of the arrow V in FIG. 1,

FIG. 6 shows diagrammatically, on a larger scale, a detail of FIG. la,

FIG. 7 is, on a larger scale, a side view in the direc-' tion of the arrow VII of FIG. lb, of the articulation of the jib on the carriage,

FIG. 8 is a side view, partly broken away, of a feedercrusher in accordance with the invention, provided in the installation according to the invention,

FIG. 9 is a longitudinal view in elevation, partly broken away, of the feeder-crusher in FIG. 8,

FIG. is a longitudinal view in elevation of a special form of embodiment of the chassis of the installation in FIGS. 1 and 2,

FIGS. 11a and 11b show in plan a modified form of embodiment of the installation according to the invention, the two Figures joining up at the line B-B,

FIG. 12 is a longitudinal view in elevation of the chassis in FIGS. 11a and 11b,

FIG. 13 shows in longitudinal elevation a variant of the chassis of the installation in FIGS. 11a and 11b, and

FIG. 14 shows in plan another special form of embodiment of the installation according to the invention.

In the Figures the same reference numbers indicate identical elements.

In a first form of embodiment represented in FIGS. 1 to 9, the installation according to the invention comprises a chassis designated by reference numeral 1. The chassis 1 is mounted on caterpillar tracks 2 ensuring its movement over the floor of the workings, for example a quarry or open-cast mine. In accordance with the invention a frame 4 is fixed to the upper part of the chassis 1 by means of universal joints 5 which allow swinging movements of the frame 4 on the chassis 1, both parallel and transverse to. an axial plane of the chassis l. Jacks 57 are arranged between the chassis 1 and the frame'4 to ensure the desired orientation of the frame 4 on the chassis l. A platform '7. is articulated on the frame 4 about a pivot 6, substantially perpendicular to the frame 4. The pivot 6-is formed by a trunnion fixed to the platform 7 and mountedrotationally in a bearing fixed onto the frame 4. The trunnion and the bearing can constitute for example two cages of a ball or roller bearing. 1 v

The jacks 57 are controlled by a stabilizing device, for example a set of gyroscopes ensuring that the axis of rotation of the pivot 6 remains vertical during the movement of the chassis 1 over the floor 3 of the workings in the vicinity of the extraction zone. The platform 7 bears at one of its ends ajib 8. The jib 8 is formed by two articulated arms 9 and 10 each constituted by a metal lattice structure. The arm 9 is articulated to the platform 7 on pivots 11 about an axis transverse to the arm 9 and perpendicular to the axis of rotation of the pivot 6. The arm 9 is supported by a cable 12 which is wound round a winch 13 mounted on the platform .7 and which is connected to the arm 9 by means of a pulley system. The pulley system is formed by a pulley shell 14 attached to the arm 9 and of a pulley shell 15 attached to the upper end of an upright 16 articulated to the platform 7. The arm 10 is joined to the end of the arm 9 by an articulation 17. The latter is represented in a detailed manner in FIG. 3. It is formed by a trunnion l8mounted rotationally in a bearing 20. In accordance with the invention the' trunnion 18 is articulated at the ends of two uprights 66 of the arm 9, by means of two pivots 19 about an axis substantially transverse to-the arm 9. In a similar way the bearing 20 is articulated at the ends of two uprights 67 of the arm 10, by means of two pivots 21 about an axis substantially transverse to the arm 10. Furthermore the trunnion 18 is mounted rotationally in the bearing 20 about an axis which is substantially perpendicular to the axis of the pivots 19 and to the axis of the pivots 21. The axis of the pivots 19 and the axis of the pivots 21 are substantially in the same horizontal plane.

In the articulation 17 the trunnion l8 and the bearing 20 can be two cages of a ball or roller bearing.

The other end of the arm 10 is maintained above a continuous conveyor 22 which is intended to be fed by the installation with rocks extracted in the exploitation zone of the workings in the vicinity of the chassis 1. The continuous conveyor 22 is for example constituted by a conveyor belt or by a pallet-type continuous conveyor. For this purpose a gantry 23 straddles the continuous conveyor 22 and is mounted on a roller track constituted by two rails 24 arranged on either side of this conveyor and parallel thereto. The gantry 23 supports on its upper part the end of the arm 10 by means of an articulation 25, similar to the articulation l7 and represented in detail in FIG. 4. It comprises in accordance with the invention a trunnion 26 which is articulated to two uprights 30 of the arm 10, on two pivots 27, about an axis substantially transverse to the arm.

The trunnion 26 is furthermore mounted rotationally in a bearing 28 about an axis substantially perpencidular to the axis of the pivots 27. The bearing 28 is itself articulated to the gantry 23, on two pivots, about an axis substantially transverse to the continuous conveyor 22 and to the rails 24 and substantially perpendicular to the axis of rotation of the trunnion 26 in the bearing 28. The axis of the pivots 27 and the axis of the pivots 29 are situated substantially in the same horizontal plane.

In the articulation 25, the trunnion 26 and the bearing 28 can likewise be two cages of a ball or roller hearing.

A counterweight 33 is provided to balance the weight of the arm 10 about the pivots 27. The counterweight 33, whose centre of gravity is situated below the pivots 27 and 29, assists moreover in maintaining the axis of rotation of the trunnion 26 vertically in the bearing 28, effected by the jacks 57.

It can be advantageous to provide a device for damping vertical oscillations of the jib 8, caused. by the movement of the chassis 1 over bumpy ground or by the discharge of rocks into a hopper 35 (described later) arranged on the platform 7 of the chassis 1.

In the installation of FIGS. 1a and 1b the damping device 105 is interposed between the arm 9 and the pulley shell 14. The damping device 105 represented diagrammatically in FIG. 6, comprises a spring 106 compressed between a plate 107 connected to the shell 14 and a plate 108 connected to the arm 9. The connection of the plate 108 to the arm 9 comprises a shock absorber 109. The shock absorber 109 isof the single acting type and is provided to brake any movement of the two plates 107 and 108 corresponding to a separation of the two plates from one another. Thus if the platform 7 swings in the direction of the arrow X (FIG. la) under the action for instance of the dropping of a very large lump of took into the hopper 35, the swinging is absorbed at least partly by the spring 106, which reduces several feet provided with a hydraulic damping device, the feet being retractable and able to be applied against the ground during the loading of the hopper. This system could advantageously be replaced by a resilient mounting of the hopper 35 in relation to the chassis 1, the clamping device absorbing the kinetic energy at the time of impact when the hopper is charged rapidly and discontinuously.

It is advantageous to provide in addition a locking device making it possible to prevent the relative rotation of the bearing 28 and of the gantry 23 about the pivots 29 when the gantry is stationary, so as to maintain the axis rotation of the trunnion 26 vertically in the bearing 28. There is thus prevented twisting of the jib 8 through swinging of the latter, under the action for example of i chambers of these jacks 68 are moreover in communication with one another through a pipe 75 provided with an obturation valve 76.

During the movement of the chassis 1 over the workings 3 and/or of the gantry 23 over its rails 24, the valve 72 is open. Therefore the oil in the jacks 68 can circulate freely between the chambers of the jacks68 so as to permit a free rotation of the bearing 28 on the gantry 23 about the pivots 29. When theinstallation has been placed in the desired position, the chassis 1 and the gantryv 23 then being immobilised, the valve 76 is closed, which has the effect of preventing relative rotation of the bearing 28 and of the gantry 23 about the pivots 29.

According to one variant, not shown, of the device in FIG. 7, the chambers of the jacks 68 are in communication with an oil reservoir via pipes each provided with an obturation valve, the above-mentioned pipe 75 being omitted.

This variant has the advantage of compensating in the chambers of the jacks 68 losses of oil which can occur from the obturation valves and also between the pistons 69 and cylinders 70.

In a modified form of embodiment, not shown, of the device in FIG. 7, the two chambers of each jack 68, situated on either side of the piston 69, are connected to one another by a pipe having an obturation valve, the aforementioned pipe 75 being omitted.

In order to ensure an equal variation in volume of the two chambers under the action of the displacement of the piston 69, itis necessary for it to carry a piston rod on each face.

In this modified embodiment, a single jack 68 is sufficient.

In accordance with a non-illustrated variant of this modified embodiment of the device of FIG. 7, the two chambers of each jack 68 are connected to an oil reservoir by ducts each having an obturation valve; the duct connecting the two chambers to one another is omitted.

This variant has the advantage of compensating for any oilleaks which might occur at the valves or between the piston rods 71 and the cylinders 70.

The device for locking the pivots 29 may likewise comprise two discs mounted opposite one another, one on the bearing 28 and the other on the gantry 23. The two discs have a row of perforations into which pins can be inserted in order to hold them fast in relation to one another.

To increase the rigidity of the arm 10, the uprights 30 may be extended above this arm 10 and connected thereto by struts 31 and 32.

To improve immobilisation of the jib 8 when the chassis 1 and the carriage or gantry 23 are immobilised, in particular in order to reduce its sensitivity to sidewinds, it may be advantageous to also provide a locking member for the oscillations of the frame 4 on the chassis I. This locking member may comprise for example obturation valves mounted on the supply circuits of the jacks 57.

If necessary, there may. also be provided locking members for the pivot 6 and also possibly for each of the articulations 17 and 25. Each of these locking members may comprise for example two discs or rings mounted opposite one another, respectively on the trunnion and on the bearing of the articulation; the two discs or rings have perforations into which pins can be inserted in order to hold the two discs or rings fast in relation to one another.

The installation illustrated in FIGS. 1 to 9 is intended for the removal towards the continuous conveyor 22 of rocks extracted in the neighbourhood of the chassis 1. For this purpose, the platform 7 has a continuous conveyor 34 and a hopper 35 for supplying this conveyor. This hopper 35 may for example be supplied with rocks by an excavator or another loading machine arranged on the floor 3 of the workings, in the neighbourhood of the chassis 1. The conveyor 34 may consist of a conveyor belt mounted between a drive cylinder 36 and a return cylinder 37 and supported by intermediate rollers 38. The conveyor belt 34 is intended for the conveying of rocks towards a hopper 39 overhanging a continuous conveyor 40 mounted on the arm 9. The conveyor 40may be a conveyor belt mounted between a drive cylinder 41 and a return cylinder 42 and supported by intermediate rollers 43. The conveyor 40 leads to the end of the arm 9 above a hopper 44 fixed to the arm 9. the hopper 44 discharges into a hopper 77 which axially crosses the trunnion 18 and ends above a continuous conveyor 45 borne by the arm 10 of the jib 8. The hopper 77 may be fixed to the trunnion 18 or tothe bearing 20. h The continuous conveyor 45 may consist of a conveyor belt mounted between a drive cylinder 46 and a return cylinder 47 and carried by intermediate rollers 48. The continuous conveyor 45 ends at the end of the jib 8 above a hopper 49 fixed to the arm 10. The hopper 49 discharges into a hopper 78 which axially crosses the trunnion 26 and ends above the conveyor 22. The hopper 78 may be fixed to the trunnion 26 or to the bearing 28. I

Guide plates 50 are provided on the arm 9 either side of the hopper 39 in order to retain on the conveyor 40 the rocks discharged onto it by the conveyor 34 via the hopper 39.

Similar plates 51 are provided on the arm 10 in the neighbourhood of the lower end of the hopper 77. The 

1. An installation for the evacuation of material comprising rocks or stones from a work site, comprising: a hopper (35) for receiving said material, an upper framework (60) supporting said hopper (35), an intermediate framework (4) carrying the upper framework (60), an articulated connection (6) by which the upper framework (60) is mounted on the intermediate framework (4) for rotation about a substantially vertical axis, a lower framework (1) mounted on crawler treads (2) for moving over the ground and supporting the intermediate framework (4), stabilization means (5, 57) for maintaining the intermediate framework (4) substantially horizontal on the lower framework (1), a first endless conveyor (34) carried by the upper framework (60) and receiving material from said hopper (35), a second endless conveyor (40) receiving material from the first conveyor (34) and in substantial alignment with the first conveyor (34), a first arm (9) carried by the upper framework (60) and carrying the second conveyor (40), articulation means (11) by which the first arm (9) is supported on the upper framework (60) for vertical swinging movement about a substantially horizontal axis, a third endless conveyor (45) receiving material from the second conveyor (40), a second arm (10) suspended from the first arm (9) and carrying the third conveyor (45), articulation means (17, 20, 21) between the first (9) and second (10) arms for mounting the second arm (10) for vertical and horizontal swinging movement relative to said first arm (9), a second hopper (44, 51) in at least two portions of which the upper portion (44) is carried by the first arm (9) and receives material from the second conveyor (40) and of which the lower portion (51) is carried by the second arm (10) and receives material from the upper portion (44) to feed material to the third conveyor (45), a discharge conveyor (22) for said material, a mobile gantry (23) movable along the discharge conveyor (22) and supporting the second arm (10) at the end of the second arm opposite the first arm (9). articulation means (27-29) between the second arm (10) and the gantry (23) for movement of the second arm relative to the gantry about horizontal and vertical axes, at least one counterweight (33) carried by the second arm (10) to balance the second arm about the articulation means (27-29), and a discharge hopper (49, 78) in at least two superposed portions of which the upper portion (49) is carried by the second arm (10) and receives material from the third conveyor (45) and of which the lower portion (78) is carried by the gantry (23) and receives material from the upper portion (49) for transmitting the material to the discharge conveyor (22).
 2. An installation as claimed in claim 1, in which said articulated connection (6) of the upper framework (60) to the intermediate framework (4) comprises a trunnion having upper and lower races the upper of which is fixed to the upper framework (60) and the lower of which is fixed to the intermediate framework (4).
 3. An installation as claimed in claim 1, in which said stabilization means (5, 57) comprises a universal joint (5) and jacks (57) carried by the lower framework (1) and acting on the intermediate framework (4).
 4. An installation as claimed in claim 1, in which the articulation means (17, 20, 21) of the second arm (10) to the first arm (9) comprises a trunnion (17, 18, 20) disposed about a vertical axis and having an upper race (18) fixed to the first arm (9) by means of substantially horizontal pivots (19) and having a lower race (20) connected to the second arm (10) by means of substantially horizontal pivots (21), the axes of said pivots (19 and 21) being coplanar.
 5. An installation as claimed in claim 1, in which the articulation means (25-29) of the second arm (10) on the gantry (23) comprises a trunnion (25, 26, 28) disposed on a substantially vertical axis and having an upper race (26) which supports the second arm (10) by means of substantially horizontal pivots (27) and having a lower race (28) carried by said gantry (23) by means of substantially horizontal pivots (29) the axes of said pivots being coplanar, and jacks (68) acting between the gantry (23) and said lower race (28) thereby to maintain the axis of the trunnion substantially vertical.
 6. An installation for the evacuation of material comprising rocks or stones from a work site, comprising: a hopper (35) for receiving said material, vehicle means (1, 2, 4, 60) mounting said hopper for movement over the ground, first endless conveyor means (34 and 40) mounted on the vehicle means for receiving material from the hopper (35), second endless conveyor means (45) receiving material from the first conveyor means (34 and 40), means interconnecting the first and second conveyor means at least for relative horizontal swinging movement about a vertical axis, a discharge conveyor (22) for the material, a gantry (23) movable along the discharge conveyor (22) and supporting an end of the second conveyor means (45) remote from the first conveyor means (34 and 40), a trunnion (26, 28) having two portions (26 and 28) rotatable relative to each other about a substantially vertical axis, means (27) interconnecting one (26) of said trunnion portions with said second conveyor means (45) for relative vertical swinging movement about a first substantially horizontal axis transverse to said second conveyor means (45), and means (29) interconnecting the other (28) of said trunnion portions with said gantry (23) for relative vertical swinging movement about a second horizontal axis transverse to said discharge conveyor (22).
 7. An installation as claimed in claim 6, in which said first and second horizontal axes are substantially coplanar. 